valpass — Variably reverberates an input signal with a flat frequency response.
imaxlpt -- maximum loop time for klpt
iskip (optional, default=0) -- initial disposition of delay-loop data space (cf. reson). The default value is 0.
insmps (optional, default=0) -- delay amount, as a number of samples.
krvt -- the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude).
xlpt -- variable loop time in seconds, same as ilpt in comb. Loop time can be as large as imaxlpt.
This filter reiterates input with an echo density determined by loop time ilpt. The attenuation rate is independent and is determined by krvt, the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude). Its output will begin to appear immediately.